Answer:
10% of 250 = 25.
When getting an increase, (using ^ for this example) add 25 to 250, getting 275. That's one increase of 10%. For an increase of 5 years (x = 5) divide 250/10=25, then multiply 25x5=125. That is the increase number. Add 125+250=375. Y=375
X = 5, Y = 375
